This invention relates to a master plate treating device.
In an offset duplicating machine, a master plate wound on the master cylinder is treated with a desensitizing or so-called ink-repellent etching solution so that no ink may be applied to regions of the plate other than the region of the image thereon, ink is supplied to the etched master plate to form an ink image which is transferred to the blanket cylinder, and the ink image formed on the blanket cylinder is transferred to sheets by pressing each sheet between the blanket cylinder and the impression cylinder, whereby a number of copies of the master plate can be produced. Since the etching solution is liable to cause erosion of components of the duplicating machine, it is desirable that the etching solution be removed from the main body of the duplicating machine and each master plate is treated with an etching solution each time it is prepared by an electrophotographic copying apparatus. To this end, a master plate prepared by the electrophotographic copying apparatus is preferably treated beforehand with an etching solution, the etching solution is dried, and water is applied to the master plate when printing is carried out so as to restore the etching solution to an active state.
The practice of preparing master plates for offset duplicating machines by an electrophotographic copying apparatus has become popular. As a final step of preparing of a master plate, the developed image is heated for fixing the same in a copying machine when using a dry developing agent, and the developing liquid adhering to the master plate is dried in a copying apparatus when using a liquid developing agent. Thus, the master plate treatment device should be of a construction such that heating the master plate after developing, applying an etching solution to the master plate and drying the applied etching solution can be performed by a simple mechanism.